Question

我必须从C ++客户端接收UDP数据报。客户端正常工作并将数据报发送到我编译此代码的ip。数据报的大小为800字节。当我发送数据报时，读取过程被阻止。我在此示例后创建了此代码：{{3}}，这在我的主机上完美运行。有什么想法吗？

procedure RECEIVE_DATA (
                         DEST_UDP_PORT        : In  WORD_TYPE;
                         SRC_UDP_PORT         : In  WORD_TYPE;
                         WAIT_TIME       : In  DURATION;
                         MESSAGE_ADDRESS : Out System.Address;
                         WAIT_RESULT     : Out Boolean
                         ) is

task Receive is
    entry Start;
end Receive;

task body Receive is
    Address  : Sock_Addr_Type;
    Socket   : Socket_Type;
    Channel  : Stream_Access;
    Receive_Timeout : constant Duration := WAIT_TIME;
    Offset : Ada.Streams.Stream_Element_Count;
    Data   : Ada.Streams.Stream_Element_Array (1 .. 800);
begin
    accept Start;
    Initialize;
    WAIT_RESULT := False;       
    Create_Socket (Socket, Family_Inet, Socket_Datagram);
    Set_Socket_Option (Socket => Socket,
                       Option => (Gnat.Sockets.Receive_Timeout, Timeout => Receive_Timeout));

    Address.Addr := Inet_Addr(DEST_UDP_IP);
    Address.Port := Port_Type(DEST_UDP_PORT);
    Bind_Socket (Socket, Address);

    Address.Addr := Inet_Addr(SRC_UDP_IP);
    Address.Port := Port_Type(SRC_UDP_PORT);
    Channel := Stream (Socket, Address);

    loop
        Ada.Streams.Read (Channel.All, Data, Offset);
        exit when Offset = 0;
    end loop;
    Free (Channel);
    Close_Socket (Socket);
    WAIT_RESULT := True;
    MESSAGE_ADDRESS := Data'Address;

    exception when E : others =>
        Ada.Text_IO.Put_Line
        (Exception_Name (E) & ": " & Exception_Message (E));
         WAIT_RESULT := False;
         Free (Channel);
         Close_Socket (Socket);
end Receive;

begin
    Initialize (Process_Blocking_IO => False);
    Receive.Start;
    Finalize;
end RECEIVE_DATA;

Answer 1

您是否尝试过使用GNAT.Sockets.Receive_Socket？ Streams使用TCP，您无法流式传输数据报。

示例：

客户端：

file.exists(n)

服务器：

with Ada.Streams;
with Ada.Text_IO;

with GNAT.Sockets;

procedure UDP_Client is
   use GNAT.Sockets;
   Address : Sock_Addr_Type;
   Socket : Socket_Type;
   Data : constant Ada.Streams.Stream_Element_Array (1 .. 512) := (others => 42);
   Last : Ada.Streams.Stream_Element_Offset;
begin
   Address.Port := 50001;
   Address.Addr := Inet_Addr ("127.0.0.1");
   Create_Socket (Socket, Family_Inet, Socket_Datagram);
   Send_Socket (Socket, Data, Last, Address);
   Ada.Text_IO.Put_Line ("last :" & Last'Img);
end UDP_Client;

流读取阻塞UDP GNAT

1 个答案: